This project has two objectives: (1) To explore the metabolic capabilities of invertebrate species, with emphasis on the ability to metabolize common environmental pollutants. Initially we are studying compounds whose metabolism is well understood in mammals, in order to make comparisons. (2) To investigate the possibility that some types of metabolism studies, especially those which must be performed in vivo, can be effectively accomplished in species having less developed nervous systems (and are thus presumably less subject to pain and distress) than the more commonly used rodent species. We are presently studying Lumbricus terrestris, the common earthworm ("night crawler") because it has been relatively neglected in studies of metabolic capabilities, and because it is typically exposed to environmental pollutants in landfills. We have established that earthworms, in symbiosis with a single species of intestinal bacteria, metabolize phthalate plasticizers completely to carbon dioxide. This may be an ideal model in which to study cooperative metabolism, since the biological system can be simplified to just two species. Earthworms appear to have very limited ability to regulate the lipid composition of their tissues. It is possible to modify the lipid composition extensively by dietary control, which may be useful in future studies.